Atmospheric Neutrinos
This paper is a brief overview of the theory and experimental data of atmospheric neutrino production at the fiftieth anniversary of the experimental discovery of neutrinos.
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arXiv subjects
Thomas K. Gaisser
Publications and source records attributed to Thomas K. Gaisser.
TeV Particle Astrophysics II: Summary comments
A unifying theme of this conference was the use of different approaches to understand astrophysical sources of energetic particles in the TeV range and above. In this summary I review how gamma-ray astronomy, neutrino astronomy and (to some extent) gravitational wave astronomy provide complementary avenues to understanding the origin and role of high-energy particles in energetic astrophysical sources.
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Cosmic Rays at the Knee
Several kinds of measurements are combined in an attempt to obtain a consistent estimate of the spectrum and composition of the primary cosmic radiation through the knee region. Assuming that the knee is a signal of the high-energy end of a galactic cosmic-ray population, I discuss possible signatures of a transition to an extra-galactic population and how they might be detected.
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High-energy Cosmic Rays
After a brief review of galactic cosmic rays in the GeV to TeV energy range, we describe some current problems of interest for particles of very high energy. Particularly interesting are two features of the spectrum, the `knee' above $10^{15}$ eV and the `ankle' above $10^{18}$ eV. An important question is whether the highest energy particles are of extra-galactic origin and, if so, at what energy the transition occurs. A theme common to all energy ranges is use of nuclear abundances as a tool for understanding the origin of the cosmic radiation.
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Atmospheric Neutrino Fluxes
Starting with an historical review, I summarize the status of calculations of the flux of atmospheric neutrinos and how they compare to measurements.
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Outstanding Problems in Particle Astrophysics
The general features of the cosmic-ray spectrum have been known for a long time. Although the basic approaches to understanding cosmic-ray propagation and acceleration have also been well understood for many years, there are several questions of great interest that motivate the current intense experimental activity in the field. The purpose of this lecture is to introduce the main topics of the School and to relate the theoretical questions to the experiments that can answer them.
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Atmospheric Neutrino Fluxes
This talk is a status report on calculations of the flux of atmospheric neutrinos from the sub-GeV range to E_ν~ PeV. In the lower energy range (E_ν< 1 TeV) the primary interest is in using the atmospheric neutrino beam to study neutrino oscillations. In the TeV range and above, atmospheric neutrinos are a calibration source and background for neutrino telescopes.
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Semi-analytic approximations for production of atmospheric muons and neutrinos
Simple approximations for fluxes of atmospheric muons and muon neutrinos are developed which display explicitly how the fluxes depend on primary cosmic ray energy and on features of pion production. For energies of approximately 10 GeV and above the results are sufficiently accurate to calculate response functions and to use for estimates of systematic uncertainties.
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Origin of Cosmic Radiation
I give a brief overview of cosmic ray physics, highlighting some key questions and how they will be addressed by new experiments.
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High Energy Neutrino Astronomy - the cosmic-ray connection
Several of the models for origin of the highest energy cosmic rays also predict significant neutrino fluxes. A common factor of the models is that they must provide sufficient power to supply the observed energy in the extragalactic component of the cosmic radiation. The assumption that a comparable amount of energy goes into high-energy neutrinos allows a model-independent estimate of the neutrino signal that may be expected.
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Antiprotons at Solar Maximum
New measurements with good statistics will make it possible to observe the time variation of cosmic antiprotons at 1 AU through the approaching peak of solar activity. We report a new computation of the interstellar antiproton spectrum expected from collisions between cosmic protons and the interstellar gas. This spectrum is then used as input to a steady-state drift model of solar modulation, in order to provide predictions for the antiproton spectrum as well as the antiproton/proton ratio at 1 AU. Our model predicts a surprisingly large, rapid increase in the antiproton/proton ratio through the next solar maximum, followed by a large excursion in the ratio during the following decade.
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Primary Cosmic-ray Spectrum and the Intensity of Atmospheric Neutrinos
Measurements of the intensity of primary cosmic-ray protons reported in the last two years suggest a lower normalization than some earlier measurements. Here we comment on the measurements, compare them to assumptions made in two independent calculations of atmospheric neutrinos and discuss the possible consequences for interpretation of measurements of atmospheric neutrinos.
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Fluxes of Atmospheric Neutrinos and Related Cosmic Rays
The atmospheric neutrino beam simultaneously spans a range of pathlengths from ten to ten thousand kilometers, which correspond respectively to downward- and upward-going neutrinos. As with any neutrino oscillation experiment, also in this case the interpretation of the data depends on a detailed knowledge of the neutrino beam. The ingredients are the primary spectrum of cosmic-ray nucleons, the geomagnetic fields in which the charged particles propagate and the properties of interactions of hadrons in the atmosphere. In this talk I review the status of calculations in light of the recent evidence for neutrino oscillations from Super-Kamiokande (Y. Fukuda et al., Phys. Rev. Letters 81 (1998) 1562).
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